In the field of aircraft landing gear, it is common practice to measure the speed of rotation of the braked wheels to ensure the regulation of the braking. To this end, it is known practice to install a tachometer in the hub whose shaft protrudes from the hub such that its end is driven in rotation by a cap secured to the wheel. The tachometer delivers a signal representative of the speed of rotation of the wheel. To this end, the wheel cap comprises a central housing in which the end of the shaft of the tachometer is engaged. The driving is ensured by the non-circular section (for example hexagonal or splined) of the end of the shaft of the tachometer and of the housing. It has emerged that, at low speed, the signal from the tachometer is sometimes noisy to the point of not being able to be used effectively for the regulation of the braking.
Efforts have of course been made to try to filter the signal from the tachometer, but the noise is sometimes so great that it completely masks the useable information.